A major barrier to the development and deployment of distribution channels for motion imagery content (e.g., video download, digital cinema) is the concern of content providers that their copyrighted material may be copied and subsequently distributed without appropriate authorization. Encryption is an important component of a Digital Rights Management (DRM) approach to controlling access to the content. However, once access has been granted, the decrypted content is left unprotected. Thus, encryption alone cannot prevent all instances of theft. Persistent access control methods that rely on proprietary file formats and the use of compliant devices have been proposed, but ultimately all video content must be converted to pixel brightness and color for display. At this point, video is vulnerable.
Given these potential leaks, a content owner needs forensic tools that enable the tracking of unauthorized copies back to the party who licensed the use of the content and who was responsible for preventing its further distribution. The ability of content owners to identify the exact distribution point at which material was pirated can be used as a tool to identify the responsible parties and can act as a deterrent to such theft. A watermark (e.g., a superimposed pattern on the digital imagery content) can uniquely identify, in the content itself, the licensee of that particular copy of the content, thereby providing content owners with a powerful tool against piracy.
According to SMPTE DC28.4 for Download Watermarks and Exhibition Watermarks, a watermark used for purchaser identification should: (a) satisfy the high-fidelity requirements of the content owners; (b) be robust to the combination of exhibition capture and compression; and (c) be secure against unauthorized removal and/or embedding. Unfortunately, no single watermark technology has demonstrated simultaneously acceptable performance in terms of fidelity, robustness and security.
Thus, there is a need in the art for a method and apparatus for providing asymmetric watermark carrier.